Stop / start video sounds like you do not have enough bandwidth on your internet connection to receive video without it spooling in between bits. Video, depending on the source, transmits between 24 and 30 frames per second. If you only have enough bandwidth to download say 20 frames per second, you get a pause while it downloads say 200 frames. It then plays - roughly - 8 seconds worth of video, and then pauses again to catch up on the next 200 frames.
It might be well worth your while running a 'Speedtest' on your internet connection. Speedtest is a free web-site here -
For a one-off test you don't even have to log-in. If you wish to keep a record of your tests over time then you do need to create an account, which is also free. Just go to the web-site, wait it for to load, then click on the large button 'Start test'.